Students research on a subject that belongs to one of the 6 chosen courses and write a piece of writing of 4000 words excluding footnotes, bibliography, references and abstracts. The students hold regular meetings with their advisors, but the advisor recommends only the necessary resources that the student should pay attention to. The teacher does not correct the drafts, does not select the essay topic and does not control the calculations. After the thesis is completed, it is evaluated and scored by an expert appointed by IB.

https://www.ibo.org/programmes/diploma-programme/curriculum/extended-essay/what-is-the-extended-essay/